1. Field of the Invention
The present invention relates to a transparent conductive film used, for example, in a capacitance-type touch panel.
2. Description of Related Art
A conventional transparent conductive film comprises: a substrate; transparent conductor layers formed on both surfaces of the substrate; and a metal layer formed on each transparent conductor layer (for example, JP-A-2011-60146). When a conventional transparent conductive film is used for a capacitance-type touch panel, metallic wiring is formed outside a touch input region by processing a metal layer. This enables a frame portion of the capacitance-type touch panel narrower. A substrate composed of a polyethylene terephthalate film (crystalline polymer film) is used for the conventional transparent conductive film. The polyethylene terephthalate film (crystalline polymer film) has a great birefringence and the birefringence differs according to the place. As a result, the conventional transparent conductive film has color irregularity (shading of color). The polyethylene terephthalate film generally has a birefringence of 0.01 or so.
A non-crystalline polymer film has a smaller birefringence and is uniform compared with the crystalline polymer film. Accordingly, color irregularity of the transparent conductive film is resolved by the use of a substrate composed of a non-crystalline polymer film. The non-crystalline polymer film is, however, weaker than a crystalline polymer film, resulting in fragile surfaces of the non-crystalline polymer film. Further, when both surfaces of the transparent conductive film have a metal layer and the transparent conductive film is rolled up to make a roll, there is a problem that adjacent metal layers of the transparent conductive film are bonded to each other by pressure. Pressure bonding is to fix by pressure and it also refers to as “blocking.”